The present invention relates to a moving staircase and more particularly to an improvement in the construction of a guide for tread boards in a curved moving staircase which has a curved conveying path in plan view.
In a conventional moving staircase of this kind, as shown in FIGS. 1 to 3 of the attached drawings, a main frame 1 of the moving staircase having a semicircular configuration in plan view is arranged substantially obliquely upwards. Supported in an endless fashion by the main frame 1 is a conveyor passage 2 which includes an inclined upper load run 2a on the upper side of the main frame 1, horizontal deflection portions 2b at both ends of the main frame 1, and an inclined lower return run 2c on the lower side of the main frame 1. The conveyor passage 2 comprises a number of tread boards 3 articulated together, each having generally the shape of a sector in plan view and provided on its underside at the forward end thercof (relative to the direction of movement) with a rotatable horizontal tread board axle 3a extending in the widthwise direction. The axle 3a fixedly carries a bracket 7a at its outer end portion which rotatably supports a pair of outer drive rollers 3b, while the axle 3a rotatably supports an inner drive roller 3c, the outer and inner drive rollers 3b and 3c being supported on and guided by outer and inner drive rails 4a and 4b, respectively, which are disposed within the main frame 1 along the outer and inner peripheries of the conveyor passage 2 and secured to the main frame 1 at the outer and inner arcuate peripheries thereof, respectively, by any suitable means such as brackets. An outer and inner follower roller, similar to the follower rollers 20a and 20b shown in FIGS. 5 and 6 to be referred to later, but not visible in FIG. 3, are provided on the tread board 3 on its underside at the rear end thereof (relative to the direction of motion), and are adapted to be supported on and guided by outer and inner follower rails 5a and 5b secured to the main frame 1 along the outer and inner peripheries of the conveyor passage 2, respectively, by any suitable means such as brackets. The tread board axles 3a are connected together at their outer and inner ends by endless outer and inner tread board chains 6a and 6b, respectively. Further, each tread board axle 3a is provided at its outer end portion with a side roller 7 rotatably mounted on the bracket 7a with the side roller 7 disposed at right angles to the outer drive rollers 3b, the side roller 7 being adapted to be abutted against a guide rail 8 which is fixedly secured to the main frame 1 through a bracket along the outer periphery of the circular arc of the conveyor passage 2, the side roller 7 serving to carry a load directed to the center of the circular arc of the conveyor passage 2 in cooperation with the guide rail 8, the load being generated as the result of the moving of the tread boards 3. Reference numeral 9 denotes a driving means provided at the upper deflection portion 2b of the conveyor passage 2 and supported by the main frame 1, comprising a driving motor 9b and a pair of sprocket wheels 9a transversely spaced apart and adapted to be driven by the driving motor 9b, receiving thereon the endless tread board chains 6a and 6b, respectively, of the tread boards 3 at the upper deflection portion 2b. 10 denotes a tension wheel means provided at the lower deflection portion 2b of the conveyor passage 2. The tension wheel means 10 is provided with outer and inner sprocket wheels 10a and 10b, respectively, which are spaced apart in the widthwise direction, the sprocket wheels 10a and 10b being adapted to have reeved thereon the outside and inside tread board chains 6a and 6b, respectively. Accordingly, the diameter of the outer sprocket wheel 10a is larger than that of the inner sprocket wheel 10 b.
The construction of the outer and inner drive rails 4a and 4b will be more precisely explained taking the inner drive rail 4b as an example. In the prior art apparatus of FIGS. 1-3, just as shown in FIG. 10 for the apparatus of this invention, the inner drive rail 4b belonging to the upper load run 2a of the conveyor passage 2 switches over at its lower end portion to a horizontal inner drive rail 4b' at the inner end of the lower deflection portion 2b of the conveyor passage 2, the drive rail 4b' terminating in an inclined portion 4b", the free end of which is bent downward substantially towards the center of the lower deflection portion 2b.
Similarly, the drive rail 4d belonging to the lower return run 2b switches over at its lower end portion to a horizontal inner drive rail 4d' at the inner end of the lower deflection portion 2b, the drive rail 4d terminating in an inclined portion 4d", the free end of which is bent upwards substantially towards the center of the lower deflection portion 2b. At this point it should be noticed that the other rails shown in FIG. 10 such as those designated by reference numerals 12b and 12d are not provided in the conventional staircase and will be described fully later on in connection with the present invention. This applies also to all of FIGS. 8 to 11.
Upon energizing the driving means 9, the sprocket wheels 9a are driven, and the tread boards 3 are driven through the outer and inner tread board chains 6a and 6b which are reeved on the sprocket wheels 9a. Therefore, the outer and inner drive rollers 3b and 3c, the follower rollers 20a and 20b, and the side rollers 7 of the tread boards 3 are guided along the upper load run 2a of the conveyor passage 2 by the drive rails 4a and 4b, the follower rails 5a and 5b, and the guide rail 8, respectively, and roll on them so that the tread boards 3 are circulated along the conveyor passage 2. In this case, the tread boards 3 are subjected to a component of force directed towards the center of the circular arc of the conveyor passage 2, the component being carried by the side rollers 7 and by the guide rail 8 guiding them.
However, in the conventional curved moving staircase as shown in FIG. 3, there are no pusher rails to prevent the drive rollers 3b and 3c from being raised up from the drive rails 4a and 4b at the inclined portions 2a and 2c of the conveyor passage 2 other than at certain sections where the drive rollers 3b and 3c are subjected to forces urging them upwards.
However, with the construction shown in FIGS. 1 to 3, although a force to urge the drive rollers 3b and 3c upwards is not usually applied to them during their normal movement, should the drive rollers 3b and 3c be raised up for some unavoidable reasons, the side rollers 7 can come off the guide rail 8 so that the tread boards 3 may be displaced towards the center of the circular arc of the conveyor passage 2 due to the force applied thereto in that direction or in the direction of the tread board axle 3a. Further, the drive rollers 3b and 3c may also be raised up from the drive rails 4a and 4b, such as during their travel along the upper load run 2a, endangering the passagers.
Moreover, since in the above-described conventional moving staircase, the guide rail 8 for the side rollers 7 is independent of the drive rails 4a and 4b, the number of parts becomes large, necessiating considerable time for manufacture, assembly, and adjustment, of a moving staircase of this kind.
On the other hand, at the lower deflection portion 2b, for instance, as shown in FIG. 10, the inner drive rails 4b and 4d are connected at their lower ends to the horizontal inner drive rails 4b' and 4d', respectively. These rails cause the endless inner tread board chain 6b to smoothly mesh with the sprocket wheel 10b having a smaller diameter than the sprocket wheel 10a, the larger sprocket wheel 10a being adapted to mesh with the outside tread board chain 6a.
As can be easily understood, in the conventional moving staircase of this kind, the rails 4b, 4b', 4b", 4d, 4d', 4d", etc. are all fixedly secured to the main frame 1, and the tension wheel means 10 are adapted to be shifted substantially horizontally outwards relative to the conveyor passage 2 as the tread board chains 6a and 6b elongate due to wear, etc. so that any slack in the chains can be compensated for. In this case, in a usual straight moving staircase such as is shown in FIG. 11, the outer drive rail 4b or the rails which correspond to the rails 4b, 4d, etc. of FIG. 10 have no inclined rails such as 4b", 4d" at their lower deflection portion 2b. Therefore, even if the inner sprocket wheel 10b is shifted by an amount W as shown in FIG. 11, it does not cause any problems in the operation of the escalator.
Contrarily, in the curved moving staircase shown in FIG. 10, since the inner drive rails 4b and 4d are provided with the horizontal rail portions 4b', 4d' as well as the inclined rail portions 4b" and 4d", if the inner sprocket wheel 10b is shifted outwards by the same distance W as in FIG. 12, it causes several problems. That is, the inner drive rollers 3c are caused to deviate from the rail portions due to the gradual increase in the distance between the tread board chain 6b and the inclined inner rail portions 4b" and 4d" as will be readily seen from FIG. 12, with the result that the inner drive rollers 3c are made unstable or can not ride smoothly on the rails, causing oscillations, noise, etc. or even damaging the machine parts.